Hi all, I've written a very short (about 5 pages of meat) Internet-Draft describing the issues and operational approaches to the problems faced with doing tunneling in the network -- as these issues kept coming up again and again with IP-in-IP, GRE, L2TP, etc. The approaches may be different for passive monitoring ('wiretapping' etc.) and 'active' tunneling. The document is about to be IETF Last Called for Informational RFC, but prior to that, I'd like to solicit comments/feedback/review from the people here because I'm 100% sure a lot of people have been faced with these issues (we certainly have..). Please send comments to me by the end of this week, either on- of off-list, as you deem appropriate. Find it at: http://www.ietf.org/internet-drafts/draft-savola-mtufrag-network-tunneling-0... Abstract Tunneling techniques such as IP-in-IP when deployed in the middle of the network, typically between routers, have certain issues regarding how large packets can be handled: whether such packets would be fragmented and reassembled (and how), whether Path MTU Discovery would be used, or how this scenario could be operationally avoided. This memo justifies why this is a common, non-trivial problem, and goes on to describe the different solutions and their characteristics at some length. -- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings